1. Field of the Invention
This invention relates generally to remotely operated well borehole or sub-sea tools for oilfield use, and more particularly, for a one shot valve useful for activating such well tools or sub-sea devices in a safe and reliable manner.
2. Background of the Related Art
Well services or completion tools and some sub-sea devices have been designed to operate from hydrostatic pressure. Typically, in operation such tools expose one side of a piston or operating rod to hydrostatic pressure upon receipt of a command with the opposite side of the piston being at atmospheric or a much lower pressure. The pressure differential causes the piston or operating rod to move (do work) and this motion causes the desired tool or device actuation or deployment.
For example, in a well working tool such as a packer, when the tool is run into the borehole on either wireline, coiled tubing or production tubing, an internal piston working in a cylinder with atmospheric pressure maintained upon either end is provided. As the tool is located in a desired position or depth in the borehole, a valve is actuated on command to expose one side of the piston or operating rod to hydrostatic well pressure. This causes a differential pressure force to be applied to the piston which, in turn, causes the piston to move. This force and movement is then mechanically coupled to perform various sub-surface functions as desired, such as setting a packer or setting a wire line locking and pack off device.
There is need for a safe, small, simple and reliable remotely operated electrically actuated valve for use in tools such as these mentioned above.
For these and other reasons, it would be desirable to have a one-shot command activated valve for activating sub-sea or well working tools which is not triggered by random electrical spikes, electrical fields from equipment, or stray ground current on the floor of an offshore platform. The present invention provides such a safe, reliable, one shot activating valve for opening a port in a well tool or sub-sea device to hydrostatic pressure.
In some prior art tools, pyrotechnic or explosive operated valves have been utilized. It is apparent that a differential pressure valve, such as provided in the present invention would provide a much safer device to transport, or use, in a hazardous environment. The lack of pyrotechnic or explosive substances in the operation of the present valve also renders it much less subject to regulation by governmental agencies and transportation services.
The present invention comprises a novel one shot electrically activated valve for use in well boreholes or sub-seal tools or devices. The device comprises a normally closed valve configured to open one time and stay open. The valve has an inlet port or ports and outlet port or ports, normally closed, and is insertable into a host device or tool to be pressure activated by opening the inlet and outlet port or ports to communicate hydrostatic pressure to the host tool. The valve has a body member and shiftable valve means, movable relative to the body member, and having sealing members to initially block fluid passage from the inlet port to the outlet port in the closed position and to allow passage of fluid (pressure) from the inlet port to the outlet port in the open position. The shiftable valve is spring and pressure biased to the open position. Prior to activation, it is held in the closed position by a low temperature meltable retaining pin or plug. Upon command, electrical current is conducted to a heating coil encompassing the retaining plug or pin in order to raise its temperature above its melting point. This then releases the shiftable valve which, assisted by spring and pressure bias, moves to the open position.
The invention may best be understood by reference to the following detailed description thereof, when taken in conjunction with the accompanying drawings.